The primary objective of this study is to determine if feeding preterm infants Reformulated Similac Special Care (RSSC) in-hospital and a specialized premature infant discharge formula (PDF) after hospital discharge will result in better bone mineralization compared to feeding Similac Special Care (SSC) in-hospital and Similac with Iron (SWI) after discharge. The secondary objective is to determine if there will be greater growth. The null hypothesis to be tested is that infants receiving RSSC in-hospital and PDF after discharge will not differ in bone mineral content (BMC) or growth from those fed SSC in-hospital and SWI after discharge, the current standard regimen.